progress: adjust terminal size only when output is stdout (#375)

Author: linzhp

progress/progress.go

@@ -353,9 +353,11 @@ func (p *Progress) initForRender() {
 p.updateFrequency = DefaultUpdateFrequency
 }
 
-// get the current terminal size for preventing roll-overs, and do this in a
-// background loop until end of render
-go p.watchTerminalSize() // needs p.updateFrequency
+if p.outputWriter == os.Stdout {
+// get the current terminal size for preventing roll-overs, and do this in a
+// background loop until end of render. This only works if the output writer is STDOUT.
+go p.watchTerminalSize() // needs p.updateFrequency
+}
 }
 
 func (p *Progress) updateTerminalSize() {